platform/surface: aggregator: Add dedicated bus and device type

The Surface Aggregator EC provides varying functionality, depending on
the Surface device. To manage this functionality, we use dedicated
client devices for each subsystem or virtual device of the EC. While
some of these clients are described as standard devices in ACPI and the
corresponding client drivers can be implemented as platform drivers in
the kernel (making use of the controller API already present), many
devices, especially on newer Surface models, cannot be found there.

To simplify management of these devices, we introduce a new bus and
client device type for the Surface Aggregator subsystem. The new device
type takes care of managing the controller reference, essentially
guaranteeing its validity for as long as the client device exists, thus
alleviating the need to manually establish device links for that purpose
in the client driver (as has to be done with the platform devices).

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20201221183959.1186143-7-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

2 files changed, 31 insertions, 0 deletions

diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index e377f52dbfa3..f078eeb0a961 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -246,5 +246,13 @@ int main(void)
 	DEVID(auxiliary_device_id);
 	DEVID_FIELD(auxiliary_device_id, name);
 
+	DEVID(ssam_device_id);
+	DEVID_FIELD(ssam_device_id, match_flags);
+	DEVID_FIELD(ssam_device_id, domain);
+	DEVID_FIELD(ssam_device_id, category);
+	DEVID_FIELD(ssam_device_id, target);
+	DEVID_FIELD(ssam_device_id, instance);
+	DEVID_FIELD(ssam_device_id, function);
+
 	return 0;
 }
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index fb4827027536..d21d2871387b 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1375,6 +1375,28 @@ static int do_auxiliary_entry(const char *filename, void *symval, char *alias)
 	return 1;
 }
 
+/*
+ * Looks like: ssam:dNcNtNiNfN
+ *
+ * N is exactly 2 digits, where each is an upper-case hex digit.
+ */
+static int do_ssam_entry(const char *filename, void *symval, char *alias)
+{
+	DEF_FIELD(symval, ssam_device_id, match_flags);
+	DEF_FIELD(symval, ssam_device_id, domain);
+	DEF_FIELD(symval, ssam_device_id, category);
+	DEF_FIELD(symval, ssam_device_id, target);
+	DEF_FIELD(symval, ssam_device_id, instance);
+	DEF_FIELD(symval, ssam_device_id, function);
+
+	sprintf(alias, "ssam:d%02Xc%02X", domain, category);
+	ADD(alias, "t", match_flags & SSAM_MATCH_TARGET, target);
+	ADD(alias, "i", match_flags & SSAM_MATCH_INSTANCE, instance);
+	ADD(alias, "f", match_flags & SSAM_MATCH_FUNCTION, function);
+
+	return 1;
+}
+
 /* Does namelen bytes of name exactly match the symbol? */
 static bool sym_is(const char *name, unsigned namelen, const char *symbol)
 {
@@ -1450,6 +1472,7 @@ static const struct devtable devtable[] = {
 	{"wmi", SIZE_wmi_device_id, do_wmi_entry},
 	{"mhi", SIZE_mhi_device_id, do_mhi_entry},
 	{"auxiliary", SIZE_auxiliary_device_id, do_auxiliary_entry},
+	{"ssam", SIZE_ssam_device_id, do_ssam_entry},
 };
 
 /* Create MODULE_ALIAS() statements.